'Big Diggah' dredge plan for Searsport could elevate mercury in Penobscot Bay lobsters to warning label levels

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Wednesday, May 15, 2013 - 4:30pm
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A federal plan to dredge a gigantic expansion of  the shipping basin off Searsport, Maine would not only be a taxpayer boondoggle; it could also resuspend so much methylmercury into Penobscot Bay's water column that lobsters and other shellfish harvested as far away as North Haven could be tainted to levels triggering mercury advisories. The dredge spoils disrupt clams and disrupt and other filterfeeders on the bay floor for years.   

That according to critics of the project who have urged the US Army Corps of Engineers to limit its effort in Searsport Harbor to maintenance dredging of the Mack Point dock and approaches, while dropping its economically improbable, and ecologically dangerous expansion dredging plan. 

The Searsport Harbor Improvement Project would dig out up to a million tons of sediment from the floor of Searsport Harbor from two locations: the Mack Point terminals and approaches, plus an immense bite out of the shoal separating Mack Point from Sears Island.

The Friends of Penobscot Bay letter to the Corps of Engineers warned that contaminants in the sediments to be dredged would be resuspended at levels that could raise methylmercury in lobster tails and claws to levels requiring issuance of a public health advisory.

The group cites the 2008 Penobscot River Mercury Study ordered by Federal judge Gene Carter to determine how much mercury the now defunct HoltraChem company had leaked or spilled into the tidal Penobscot River in Orrington.   

The study examined samples of sediment, fish and shellfish taken from the waters off the Holtrachem site, downriver, and throughout the upper bay to Vinalhaven. It found  high levels of the potent neurotoxin methylmercury (MeHg) were in the sediments closest to the holtrachem plant, tapering off downstream until reaching the upper bay, where the level of methylmercury rose again, tapering off to background levels in Vinalhaven

According to the report: "At the eight upper estuary sites (see map Figure 36), of 67 lobster sampled, 25% exceeded the MDEP criterion of 200 ng/g w.w. MeHg and 6% exceeded the USEPA criterion of 300 ng/g. This was calculated from the mean of total Hg in claws and tails (from individual total Hg concentration in claws assuming tail muscle was 53% higher in total Hg) and that 75% of the total Hg in both tissues was MeHg."

The Friends of Penobscot Bay warned the Corps that: "some of the most elevated  levels of mercury in lobster claws was in samples taken less than a mile away from the area proposed for improvement dredging. If more mercury were resuspended as a result of dredging, then the contaminated lobster zone – in that location already well above EPA toxicity limits – could spread to a far greater part of the bay"

The group warned  of economic disaster to the region if public health laws mandate posting a mercury advisory on Penobscot Bay lobsters and processed lobster products.

Thanks But No Tank's letter  to the Army Corps of Engineers challenges the Corps' claim that dredging is required to accommodate deep draft vessels presently using the existing terminals at the port. TBNT's attorney Steve Henchman wrote that this claim "is expressly contradicted by all of the Corps’ prior representations about Mack Point and the port of`Searsport, published in the 2012 EA regarding the proposed DCP Searsport LLC LPG marine import terminal at Mack Point."

"In that 2012 EA," the group attorney Steve Hinchman wrote, "the Corps concluded that "no dredging” would be required to accommodate the 4 to 8 ocean-going, deep draft LPG tankers that the DCP facility would have been serviced by annually — ships with an anticipated draft of up to 39.7 feet."

TBNT called this "proof that the assertions of need for the proposed "improvement" dredging in the April 5, 2013, Feasibility Study, and draft EA, FONSI and CWA letter are arbitrary and capricious — unsupported even by the Corps’ own prior, recent findings about the safety and adequacy of this port area — without any dredging — for a significant increase in large, ocean-going, deep draft tanker trafiic."

"Despite having thirteen years to conduct a thorough assessment of the alleged need to deepen the channel and pier area of Mack Point," Hinchman wrote, "the cursory and out-dated analysis on which the Corps’ April 5thFeasibility Study and draft EA, FONSI and Clean Water Act (CWA) letter, is based fails to adequately consider the potentially significant environmental damage that the direct and indirect, primary and secondary consequences of the proposed "improvement dredging" would wreak on the fragile environment of Upper Penobscot Bay, and the Bay as a whole from the dumping of almost a million cubic yards of dredge spoils that potentially contain significant contaminants (including mercury. "

Down East Lobstermen's Association also wrote to the Corps of Engineers in opposition to the dredge expansion project. DELA regularly samples the area for pollutants They warned of the complexity of the water circulation at the top of the bay and called for a public hearing and environmental impact study to learn the extent  of  methylmercury contamination of bottom dwelling species that the project would bring, and how badly the fine sediments resuspended en mass into the bay water column would suffocate bay plankton and clams and other filterfeeders. According to the group, dredging in the region in the past  depressed lobster fishering in the upper bay for nearly a decade.

Everyone hopes that the Army Corps of Engineers will drop its 'dig it and they will come' expansion plan fantasy. They must not throw Penobscot Bay's lobster fishery under the bus for a completely unnecessary expansion dredging project could taint the bay's lobsters with enough of this dangerous neurotopxin compound to require lobster processors to add mercury advisory labels to their product packaging when made from Penobscot Bay lobsters.

Background information (courtesy TBNT):

37,000 cubic yards of dredge materials would be removed as maintenance dredging. This would maintain the current federally authorized 35’ depth of the existing channel, tum around and pier areas. 892,000 cy of dredge spoils have to be removed  for the "improvement" project

An additional  31,000 cubic yards of dredge spoils would be removed from the pier area. 

The existing entrance channel and turning basin would be deepened from 35 feet to a depth of 40. The entrance channel would be widened from its current 500 feet at the narrowest point to 650 feet. A maneuvering area would be created in Long Cove adjacent to the east berth along the State Pier.

The rectangular maneuvering area would be  875 feet on the west side and 1,066’ on the east side, a width of 400 feet. This area would also be deepened to 40 feet MLLW.